package com.sxhuayuan.parking.utils;


/**
 * @项目名称：HuayuanPay
 * @类名称：IdWorker
 * @类描述：产生全局唯一的编号，可用作内部订单编号
 * @创建人：gaoyan
 * @创建时间：2016年1月9日 上午9:13:37
 * @修改时间：2016年1月9日 上午9:13:37
 * @修改备注：
 * @version 1.0
 */
public class IdWorker {
	private final long workerId;
	private final static long twepoch = 1403694295814L;
	private long sequence = 0L;
	private final static long workerIdBits = 4L;
	public final static long maxWorkerId = -1L ^ -1L << workerIdBits;
	private final static long sequenceBits = 10L;

	private final static long workerIdShift = sequenceBits;
	private final static long timestampLeftShift = sequenceBits + workerIdBits;
	public final static long sequenceMask = -1L ^ -1L << sequenceBits;

	private long lastTimestamp = -1L;

	public IdWorker(final long workerId) {
		super();
		System.out.println("maxWorkerId=" + maxWorkerId);
		if (workerId > maxWorkerId || workerId < 0) {
			throw new IllegalArgumentException(String.format(
					"worker Id can't be greater than %d or less than 0", maxWorkerId));
		}
		this.workerId = workerId;
	}

	public String nextIdStr() {
		return String.valueOf(nextId());
	}
	
	public synchronized long nextId() {
		long timestamp = this.timeGen();
		if (this.lastTimestamp == timestamp) {
			this.sequence = (this.sequence + 1) & sequenceMask;
			if (this.sequence == 0) {
				System.out.println("###########" + sequenceMask);
				timestamp = this.tilNextMillis(this.lastTimestamp);
			}
		} else {
			this.sequence = 0;
		}
		if (timestamp < this.lastTimestamp) {
			try {
				throw new Exception(String.format(
						"Clock moved backwards.  Refusing to generate id for %d milliseconds",
						this.lastTimestamp - timestamp));
			} catch (Exception e) {
				e.printStackTrace();
			}
		}

		this.lastTimestamp = timestamp;
		long nextId = ((timestamp - twepoch << timestampLeftShift))
				| (this.workerId << workerIdShift) | (this.sequence);
		// System.out.println("timestamp:" + timestamp + ",timestampLeftShift:"
		// + timestampLeftShift
		// + ",nextId:" + nextId + ",workerId:" + workerId + ",sequence:" +
		// sequence);
		return nextId;
	}

	private long tilNextMillis(final long lastTimestamp) {
		long timestamp = this.timeGen();
		while (timestamp <= lastTimestamp) {
			timestamp = this.timeGen();
		}
		return timestamp;
	}

	private long timeGen() {
		return System.currentTimeMillis();
	}
}